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51.
A fast splitting procedure for classification trees   总被引:1,自引:0,他引:1  
This paper provides a faster method to find the best split at each node when using the CART methodology. The predictability index is proposed as a splitting rule for growing the same classification tree as CART does when using the Gini index of heterogeneity as an impurity measure. A theorem is introduced to show a new property of the index : the for a given predictor has a value not lower than the for any split generated by the predictor. This property is used to make a substantial saving in the time required to generate a classification tree. Three simulation studies are presented in order to show the computational gain in terms of both the number of splits analysed at each node and the CPU time. The proposed splitting algorithm can prove computational efficiency in real data sets as shown in an example.  相似文献   
52.
品牌资产及其测量中的概念解析   总被引:18,自引:0,他引:18  
品牌资产(品牌权益)是近年来营销领域中研究的热点问题,然而对于其基本概念的曲解却阻碍了对这个重要问题的进一步研究。本文针对品牌资产涉及的几个概念(品牌资产、品牌权益、品牌价值)及其相互关系加以解释,并将主要的品牌资产的测量方法进行分类,目的是澄清人们对于品牌资产基本概念的模糊认识,为进一步深入研究指明方向。  相似文献   
53.
The MENTOR project, based at the University of Strathclyde, is producing multimedia computer based learning materials with the aim of improving both the effectiveness and the efficiency of teaching Operational Research/Management Science in higher education. The process of development has been carefully designed to encourage ownership of and commitment to the materials amongst lecturing staff in Universities, with the aim of ensuring widespread use. The paper outlines this process of development and design of materials. Experiences in introducing students to the use of these materials as an integrated part of a Management Science class are reported. Feedback from students has been very positive but also indicates the need for ongoing support and direction.  相似文献   
54.
一种基于闭排队网络的集装箱码头设备配置优化模型   总被引:5,自引:0,他引:5  
将集装箱码头龙门吊装卸工艺抽象为闭排队网络模型,采用估算均值法计算了顾客到达和服务时间分布为一般情况的闭排队网络系统性能指标.仿真结果表明,闭排队网络模型计算结果可以为集装箱码头设备配置提供一定的决策支持.  相似文献   
55.
高宽课程一日常规是幼儿一天活动的顺序,因其支持幼儿的主动性发展顺应了各国教育改革的潮流而备受推崇。但其本土化在教育实践中出现了教师没能领悟到高宽课程理念的精髓、在实践中过于注重形式、本土化探索的积极性不高等方面的“症状”。本文从文化、园长、教师和家长四个方面对上述“症状”进行了“病源”分析。最后提出在移植高宽课程一日常规时应充分考虑到文化差异、强化对高宽课程的深入研究、加强师资培训,搭建师资培训平台、重视园长培训,提供宽松的教育环境、加强家园合作,获得家长支持等五条建议,以求“对症治疗”,使高宽课程一日常规为中国学前教育事业发展提供有益的借鉴。  相似文献   
56.
One significant change in adoption practice that has occurred over the last four decades is the shift away from an expectation of confidentiality towards an expectation of openness in adoption. Openness is typically conceived in terms of the level of contact between adoptive and birth families following adoption or the extent to which adoption is openly discussed within the adoptive family. While these shifts in practice have generated controversy, they are largely supported by research evidence and have become a feature of contemporary adoptive family life. As a result, the narrative that has emerged in relation to openness in adoption is one of historical progress. In this paper, I argue that the lived reality of adoption is less straightforward than this narrative suggests. An analysis of the social and cultural context in which adoption operates suggests instead that the persistent feature of adoption throughout this historical period of increasing openness can be more accurately described as a state of enduring ambiguity regarding the nature of post‐adoption relationships. The paper highlights the potentially damaging consequences of overlooking this aspect of adoptive family life and comments on the role of policy in shaping openness in adoption.  相似文献   
57.
The aim of this article is to foster an awareness of the need for gender‐sensitive research in the context of the methodological and ethical challenges posed by such research. We trace the development of gender sensitivity and masculinity in social work practice and research and connect this to an overview of the issues posed by research on sensitive topics. Reflecting on a research project involving Chinese male sexual abuse survivors, we draw conclusions illustrating and proposing a range of methodological practices and ethical safeguards. We underscore the importance of gender‐sensitivity in performing research on sensitive topics with men in a Chinese community.  相似文献   
58.
This study examined how the cultural and situational contexts can jointly shape the consequences of discipline strategies. Israeli mothers who grew up in Israel or in the Former Soviet Union (FSU) (overall N = 110) reported regarding their use of psychologically controlling and punitive discipline with their seven‐years‐old to 10‐years‐old children, and teachers reported regarding children's behavior problems. We assessed both mothers' overall general use of the discipline strategies, and their use of the same strategies following transgressions in the academic domain, an area which the two groups emphasize to differing degrees. Consistent with hypothesis, controlling discipline in academic situations had more positive consequences in the FSU group compared with the Israeli‐origin group. In contrast, and as predicted, cultural group was not a moderator of mothers' overall, general use of the same discipline strategies. The findings illustrate how taking the situation into account can inform examination of the moderating role of cultural group.  相似文献   
59.
In the recovery of interblock information to improve the treatment differences estimates in incomplete block designs, the parameter p is usually unknown. Many authors have worked on the problem of estimating it and of studying its properties together with the properties of the treatment differences estimates. In this paper a numerically efficient algorithm is developed which yields the maximum likelihood estimates (MLE) of all the parameters in the mixed incomplete block design model (treatment effects, ρ and variance)  相似文献   
60.
Peer sociometrics and teachers' friendship reports were compared in 2179 preschool dyads. One hundred twenty of 306 reciprocated friend dyads from peer sociometric data were also identified as good friends by their classroom teachers, and 301 of 600 of non‐reciprocated dyads in peer data were named as friends by one or both classroom teachers (overall kappa = .16). Friendship classifications from both peer and teacher data had significant relations with variables relevant to peer interactions, social skills, peer acceptance, and teacher‐rated scales (six of seven tests significant for peer data; five of eight significant for teacher data). Multilevel analyses indicated that friendship status effects were not qualified by classroom‐level differences. Findings suggest that sociometric tasks can identify preschoolers' peer friendships and that the range of correlates may be broader in peer‐choice data than in teachers' friendship evaluations.  相似文献   
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